Interference

B and E Blocks took up the topic of interference of light waves today. We looked at the conditions required to produce observable interference patterns for light (must be monochromatic and coherent)and discussed Young's double-slit experiment that was used to document these patterns and provide evidence for the wave theory of light. We practiced the relevant calculations for interference and will expand these tomorrow when we look at diffraction. For B Block, this will be in lecture; for E Block, this will be in lab.

C Block discussed diffraction in class today, although we'd been skirting around the issue with our interference lecture on Friday. Looking back at Friday's slides, it was easy to see that diffraction was necessary for the wave interference patterns formed and observed and today we looked at similar slides and tossed in Huygen's principle as a bonus. The lab activity we work on tomorrow will allow you to investigation diffraction of light and use the formulas from today to calculate the wavelength of the laser pointers you use in class.

F Block worked on their diffraction and interference lab today. Groups used a diffraction grating with a known slit separation to measure the wavelength of light of two laser pointers (a red, a green and/or a violet). Then, students were given a diffraction grating with an unknown slit separation and to design a test to document that property for the grating. The formula used for the calculations was introduced at the start of class and we'll get another look at it tomorrow when we talk about diffraction.

For everyone, Wednesday is review day; Thursday is exam day for Chapters 15 and 16. Friday, we start with charge and static electricity.